There are six open chambers in the dungeon, five of which contain a pedestal with the Master Sword. If the player sets foot in one of these chambers, they will trigger a battle with Link. It is possible to avoid these battles by jumping over the chamber's floor. The sixth chamber contains the Triforce, which serves as the stage's exit. If the player defeats all five Links before reaching the Triforce, they will receive the Link Master bonus. The locations of the five Master Swords and the Triforce are random.

The Underground Maze is available through hacking. Entering one of the chambers may cause unwanted results, such as the game crashing or the match ending.

Dungeons are a core element in the majority of Zelda games. Link frequently has to navigate several of them - often centered on a specific theme like fire, water, or forest - while solving puzzles and defeating enemies and bosses in order to find magical objects and progress the plot. In particular, finding a piece of the Triforce of Wisdom (as opposed to the full Triforce in this stage) is the goal of every dungeon in the original The Legend of Zelda. The side-scrolling nature of Smash makes the Underground Maze resemble the dungeons of Zelda II: The Adventure of Link, which, unlike the rest of the main Zelda games, utilizes a side-scrolling view instead of a top-down or 3D one.

The Master Sword is a recurring legendary sword, which Link obtains by pulling it from its pedestal in both The Legend of Zelda: A Link to the Past and The Legend of Zelda: Ocarina of Time. The design of the sword and pedestal in this stage are based on their appearances in Ocarina of Time. The presence of multiple swords in this stage could be a reference to the fake swords in A Link to the Past, used as decoys for anybody in search of the real Master Sword.